This invention relates generally to improvements in so-called front end loaders of the type having an hydraulically operated frame for supporting and manipulating a bucket or scoop or other work attachment at the front of the vehicle. More specifically, this invention relates to an improved blade tilt assembly of a relatively compact and simplified design for adjusting the lateral tilt of the scoop or bucket or other attachment on the front end loader. The blade tilt assembly is particularly suited for use with relatively small so-called skid-steer front end loaders of the general type described in U.S. Pat. Nos. 3,231,117 and 3,672,521.
Front end loaders are generally known in the art for use in performing a wide range of grading, digging, construction, and other related tasks. In general terms, front end loaders typically comprise a tractor-type vehicle equipped with a pivoting frame having a selected work attachment such as a scoop or bucket connected thereto. Hydraulic actuator units are provided on the vehicle for controlled raising and lowering of the pivoting frame, in combination with controlled fore-aft pitch adjustment of the work attachment. Appropriate manipulation of the hydraulic actuator units enables the work attachment to be correspondingly manipulated to perform a specific desired task.
An exemplary front end loader is shown and described in U.S. Pat. No. 3,231,117, generally in conformance with so-called skid-steer loaders marketed by Melroe Company, Division of Clark Equipment Company, Fargo, N. Dak., under the trademark BOBCAT. Such front end loaders are adapted for relatively rapid and interchangeable mounting of different work attachments, such as scoops or buckets, dozer blades, fork lift apparatus, rotary sweepers, jackhammer and auger devices, etc. In this regard, front end loaders of this type are frequently equipped with an adapter mounting plate of the type described in U.S. Pat. No. 3,672,521, to facilitate relatively rapid interchangement of work attachments.
In many earth-moving or grading applications, the specific lateral tilt angle of the work attachment such as a scoop or bucket can be an important factor contributing to rapid completion of the desired task. By way of example, it may be extremely desirable to orient the scoop or bucket with a specific lateral tilt in the course of a landscape grading operation, or in the course of digging a swimming pool or the like to have a sloped floor surface. In this regard, a variety of mechanisms have been proposed throughout the prior art to permit such blade tilt adjustment. However, such prior art devices have typically been relatively complex and costly, frequently having a size and weight which can adversely affect the center of gravity and thus alter the maneuverability of the vehicle. Moreover, such tilt mechanisms have not been well suited for use with a relatively compact front end loader of the type described in U.S. Pat. No. 3,231,117, nor have such mechanisms been satisfactory for use with adapter mounting plates of the type described in U.S. Pat. No. 3,672,521.
Furthermore, prior tilt adjustment mechanisms have frequently been limited to hydraulic mechanisms for raising and lower one end of the scoop or bucket on the front end loader. Such single-end devices inherently require attachment support mechanisms such as ball joints or slide tracks or similar bearing support structures which exhibit relatively high wear and resultant short life-span in earth-moving applications. Moreover, raising and lowering of one end of the bucket or scoop also inherently skews the angle of attack of the work attachment, such that soil grading or shaping at significant tilt angles may not be possible.
The present invention overcomes the many problems and disadvantages presented in the prior art, by providing an improved blade tilt assembly for a front end loader, wherein the blade tilt assembly has a relatively compact and simplified design which may be conveniently used with an adapter mounting plate of the type described in U.S. Pat. No. 3,672,521. Moreover, the blade tilt assembly of the present invention provides substantially sealed bearing and support mechanisms which accommodate bidirectional raising and lowering of the opposite ends of the work attachment in substantially equal increments.